#include <cassert>
#include <iostream>
#include <vector>
#include <algorithm>
#include <utility>

#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define RFOR(i, a, b) for (int i = (b)-1; i >= (a); i--)
#define rep(i, n) for (int i = 0; i < (n); i++)
#define rep1(i, n) for (int i = 1; i <= (n); i++)
#define rrep(i, n) for (int i = (n)-1; i >= 0; i--)

#define pb push_back
#define mp make_pair
#define fst first
#define snd second
#define show(x) cout << #x << " = " << x << endl
#define chmin(x, y) x = min(x, y)
#define chmax(x, y) x = max(x, y)
#define pii pair<int, int>
#define vi vector<int>

using namespace std;
template <class S, class T>
ostream& operator<<(ostream& o, const pair<S, T>& p)
{
    return o << "(" << p.first << "," << p.second << ")";
}
template <class T>
ostream& operator<<(ostream& o, const vector<T>& vc)
{
    o << "sz = " << vc.size() << endl
      << "[";
    for (const T& v : vc)
        o << v << ",";
    o << "]";
    return o;
}
typedef long long ll;

int c1, c2, c3, c4;

int main()
{
    cin >> c1 >> c2 >> c3 >> c4;
    const long s1 = ((long)(c1 * c3) - (long)(c2 * c2));
    const long s2 = ((long)(c1 * c4) - (long)(c2 * c3));
    const long s3 = ((long)(c2 * c4) - (long)(c3 * c3));
    const long double sum = (long double)(s2) / s1;
    const long double product = (long double)(s3) / s1;
    if (sum * sum >= 4 * product) {
        cout << "R" << endl;
    } else {
        cout << "I" << endl;
    }

    return 0;
}